[docs] [issue43739] Fixing the example code in Doc/extending/extending.rst to declare and initialize the pmodule variable to be of the right type.

Change by miss-islington <mariatta.wijaya+miss-islington@gmail.com>: ---------- nosy: +miss-islington nosy_count: 4.0 -> 5.0 pull_requests: +24066 pull_request: https://github.com/python/cpython/pull/25332 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue43739> _______________________________________